White Coat, Black Art·THE DOSE | Q&A

Can contact-tracing apps really help us beat COVID-19?

Contact-tracing apps can be helpful, but they're not a silver bullet, says Dr. Prabhat Jha, director of the Centre for Global Health Research at St. Michael’s Hospital.

'There's a human nature part of this,' says Dr. Prabhat Jha

Many countries have introduced contact tracing apps to help contain the COVID-19 pandemic. (Dylan Martinez/Reuters)
Listen to the full episode26:29

This month, the federal government plans to launch COVID Alert, its free, voluntary contact-tracing app.

Ontario will be the first province to release the app, even as some people raise privacy concerns. 

But will it work?

To find out, Dr. Brian Goldman, host of The Dose talked to Dr. Prabhat Jha, director of the Centre for Global Health Research at St. Michael's Hospital, and professor of epidemiology at University of Toronto's Dalla Lana School of Public Health.

Dr. Prabhat Jha, director of the Centre for Global Health Research at St. Michael’s Hospital, and professor of epidemiology at University of Toronto’s Dalla Lana School of Public Health. (Unity Health Toronto)

So how do contact-tracing apps work?

They work on the premise that people who test positive have to voluntarily enter the information into the phone. By looking at who's been close to that phone through Bluetooth connections, they're able to let people know that they have been in contact with someone who might have had an infection. Then it's supposed to prompt those people to potentially get tested.

Bluetooth contact tracing: First, users download an app and enable bluetooth on their smartphones. Second, the app sends out a unique anonymized beacon to other devices nearby using the same app. Third, each phone records and securely stores beacons it comes in contact with. Fourth, the app downloads a list of beacons associated with anonymous app users who have tested positive for coronavirus. The device cross-checks those beacons with ones it came into contact with. If there is a positive result in the list, users receive a notification. (CBC)

How does the app know that I've tested positive for COVID-19?

It will only know if you enter that information into the app.

So there's two big conditions for the app. One, it involves people voluntarily putting in their positive status if they've been tested. The second is it works much better if it has high coverage. 

What is the biggest benefit of a contact-tracing app? 

If it encourages people to get tested then that's a good thing.... the app could help identify who's at higher risk, and those are the populations that need to get tested. But that'll all depend on how wide the coverage is. The experience of Iceland wasn't so positive. They found that only something like 35 per cent of the Iceland population took up a free app and it wasn't very useful. Likewise, the U.K. experience has been not so useful

On the other hand, the German experience has been more positive. But I attribute that to the fact that they relied on not just the app but they also had people calling you when there was a positive case. 

I think there's a human nature part of this. If I get a call from a concerned public health official saying I might have been exposed, I can interact with them. It's a human voice that's assuring me to get tested so I think the German results are good because they had a lot of people on the phones along with the app.

A recent poll of Canadians found that over half disapproved of mandating a contact-tracing app. Are we as Canadians too suspicious of the government for this app to even work?

We have to have the right balance. I think we should have more requirements to have everyone who is positive be reported and to perhaps be required to have the app.

I'm not too concerned about the privacy concerns personally because if the app is housed under public health agencies, they're not working with commercial vendors to sell your information or others. So in that sense, I trust the government more than I would Apple or Google because you know they're kind of figuring out ways of monetizing it.

Prime Minister Justin Trudeau unveils a new smart phone application designed to warn people when they have come into contact with someone who has tested positive for COVID-19. 2:39

We have to ask: What is our objective for the pandemic? The main objective is to prevent deaths in older people. If you're looking after older people or working at a nursing home, then you've got an extra obligation to make sure that you are protected. So in that case I would use the app. 

If we get a second wave, our core strategy should be really that we're not going to prevent a little bit of infection here and there in the general population as much as we'd like to, but we should absolutely focus on stopping entry into seniors' homes because they're the ones getting killed by it.


Q and A has been edited for length and clarity. 

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